Natural killer (NK)/T-cell lymphoma-associated hemophagocytic syndrome (HPS) is a rare and fatal disease with no optimal treatment. The present study reports the clinical features, diagnosis and treatment process of three patients with relapsed NK/T-cell lymphoma-associated HPS. All of the patients were classified as Ann Arbor stage IV and presented with a poor performance status. Two patients were successfully treated with a pegaspargase-containing combination regimen and one patient succumbed due to serious complications. These cases indicate that for patients with a history of lymphoma, the diagnosis of HPS should be considered when patients present with progressive high fever, pancytopenia and liver dysfunction. Early identification and effective treatments, including pegaspargase-based regimens are essential for an enhanced prognosis.